As a novel form with macroscopic appearance of strangeness in strongly interacting matter, kaon condensation has longly received much attention in the interdisciplinary fields of particle-nuclear physics, astrophysics, and condensed matter physics [1]}, [2]}, [3]}, [4]}, [5]}, [6]}, [7]}, [8]}.
Driving force of kaon condensation is the \(s\) -wave kaon (\(K\) )-nucleon (\(N\) ) interaction specified by chiral symmetry [1]}, [2]}.
Kaon condensation most likely occurs when the lowest \(K^-\)  energy, which decreases with baryon density due to the \(s\) -wave \(K\) -\(N\)  attraction, meets the electron chemical potential [3]}, [4]}. It has been shown that the equation of state (EOS) is largely softened in dense matter, once kaon condensation sets in [4]}, [8]}.
It has also been suggested that mixing of hyperons (\(Y\) ) occurs in the ground state of neutron star matter [15]}, [16]}, [17]}.
The existence of hyperons would make the EOS soft as well. These phases lead to more compact stars reducing the maximum mass of neutron star and its radius [8]}, [16]}, [17]}. They would also affect thermal evolution of neutron stars through extraordinary cooling processes via enhanced neutrino emissions [2]}, [22]}, [23]}, [24]}.
